Firefox and Thunderbird appear on the verge of deciding to part ways, but still be friends. That’s according to a recent proposal by an executive at the Mozilla Foundation to cease supporting development of the open source email client in order to focus on its Web browser.

As probably every open source fan knows, Firefox is a Web browser and Thunderbird is an email client. Both applications are open source and have been maintained by the Mozilla Foundation since the early 2000s, when Mozilla paired them in an effort to offer a comprehensive suite of Internet productivity applications for desktop computers.

A decade later, the two programs no longer complement one another, according to Mozilla Executive Chairman Mitchell Baker. Instead, Thunderbird burdens Firefox development by imposing a “tax” on manpower and development resources.

“Today Thunderbird developers spend much of their time responding to changes made in core Mozilla systems and technologies,” Baker wrote. “At the same time, build, Firefox, and platform engineers continue to pay a tax to support Thunderbird.”

Baker suggested that both Firefox and Thunderbird would be better off if they reverted to being separate projects. That would allow developers working on Firefox to focus all of their attention on that application, while Thunderbird developers could do the same for the email client.

Baker did not propose a specific plan for spinning Thunderbird off into its own project. She did make clear that Mozilla would like to make the transition smooth and that the organization will continue to support Thunderbird until a transition is complete.

Baker’s proposal is not exactly shocking. The writing has been on the wall since Mozilla announced in 2012 that it no longer intended to provide major feature enhancements for Thunderbird.

Thunderbird’s divorce from Mozilla– assuming it happens, which seems likely — probably won’t matter to too many people. The app has been more or less dead in the water already for several years, and the preponderance of webmail has made standalone email clients like Thunderbird less important today than they were ten years ago.

Still, as the only major open source email client that is also cross-platform, Thunderbird is something that some users will be sad to see disappear. Probably the only app that comes close to serving as a substitute is Evolution, which is not really cross-platform. (Some developers attempted to create a Windows port, and I can attest that it worked circa 2008, but it has long since ceased to be actively developed.) And webmail is a poor substitute for people who like added features in their email, such as PGP-based encryption. For these reasons, the open source community is likely to find some value in Thunderbird, whether it is maintained by Mozilla or another group.